1. Field of the Invention
The present invention relates to a thin film magnetic head having at least an inductive magnetic transducer for recording, a method of manufacturing the same, and a magnetic recording apparatus in which the thin film magnetic head is mounted.
2. Description of the Related Art
In recent years, in association with improvement in areal density of a magnetic recording medium (for example, a hard disk), improvement in performance of a thin film magnetic head to be mounted on a magnetic recording apparatus (for example, a hard disk drive) is demanded. Known recording methods of a thin film magnetic head are a longitudinal recording method in which the orientation of a signal magnetic field is set to an in-plane direction (longitudinal direction) of a recording medium and a perpendicular recording method in which the orientation of a signal magnetic field is set to a direction orthogonal to the surface of a recording medium. At present, the longitudinal recording method is widely used. However, when a market trend accompanying improvement in areal density is considered, it is assumed that, in place of the longitudinal recording method, the perpendicular recording method will be regarded as a promising method in future for the following reason. The perpendicular recording method has advantages such that high linear recording density can be assured and a recorded hard disk is not easily influenced by thermal decay.
A thin film magnetic head of the perpendicular recording method has a thin film coil for generating a magnetic flux and a magnetic pole layer extended rearward from the air bearing surface and emitting the magnetic flux generated by the thin film coil toward a hard disk. The magnetic pole layer includes, for example, a uniform width portion extending rearward from the air bearing surface and having a uniform width which specifies recording track width of a hard disk, and a wide portion coupled to the rear end of the uniform width portion and having width larger than the width of the uniform width portion. As a thin film magnetic head of this kind, for example, a thin film magnetic head having a configuration that a magnetic pole layer is formed partially over a yoke layer and is magnetically coupled to the yoke layer is known (refer to, for example, Japanese Unexamined Patent Application No. 2002-197611). In the thin film magnetic head of this kind, when a magnetic flux generated by the thin film coil is emitted from the uniform width portion in the magnetic pole layer to the outside, a hard disk is magnetized by a magnetic field (perpendicular magnetic field) generated on the basis of the magnetic flux, so that information is magnetically recorded on the hard disk.
To stably assure recording performance of the thin film magnetic head, for example, it is necessary to suppress unintentional writing to a neighboring track in a recording operation. The “unintentional writing to a neighboring track” is a phenomenon such that at the time of recording information onto a track to be recorded on a hard disk, a magnetic flux is emitted from the uniform width portion of the magnetic pole layer toward the track to be recorded. In addition, an unnecessary magnetic flux is unintentionally emitted to a neighboring track (a track adjacent to the track to be recorded) from the wide portion without passing through the uniform width portion. Due to this, information already recorded on the neighboring track is unintentionally overwritten. In short, the phenomenon is a problem that recorded information is erased. From the viewpoint of protection of information recorded on a hard disk, naturally, erasure of information caused by unintentional writing to a neighboring track has to be prevented as much as possible. However, the conventional thin film magnetic head has a problem such that unintentional writing to a neighboring track cannot be sufficiently suppressed depending on a structural factor of the magnetic pole layer and there is the possibility that erasure of information recorded on a hard disk is not sufficiently prevented. To spread the thin film magnetic head of the perpendicular recording method, it is urgently needed to establish a technique capable of preventing information from being erased by suppressing unintentional writing to a neighboring track. In particular, when mass productivity of the thin film magnetic head is considered, it is also important to establish a manufacturing technique capable of manufacturing a thin film magnetic head easily and stably.